30971221 has 2 divisors, whose sum is σ = 30971222. Its totient is φ = 30971220.

The previous prime is 30971207. The next prime is 30971231. The reversal of 30971221 is 12217903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20376196 + 10595025 = 4514^2 + 3255^2 .

It is a cyclic number.

It is not a de Polignac number, because 30971221 - 2⁵ = 30971189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (30971231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15485610 + 15485611.

It is an arithmetic number, because the mean of its divisors is an integer number (15485611).

Almost surely, 2^30971221 is an apocalyptic number.

It is an amenable number.

30971221 is a deficient number, since it is larger than the sum of its proper divisors (1).

30971221 is an equidigital number, since it uses as much as digits as its factorization.

30971221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 30971221 is about 5565.1793322408. The cubic root of 30971221 is about 314.0408246107.

The spelling of 30971221 in words is "thirty million, nine hundred seventy-one thousand, two hundred twenty-one".